Project summary/Abstract Cardiovascular disease is a leading cause of death globally. In vitro engineering of replacement blood vessels has emerged as a promising area of research that has the potential to provide lifesaving therapy in patients where autologous bypass grafts are not possible. The challenges of vascular tissue engineering require the developing samples to be monitored at regular intervals, however conventional assessment techniques are slow, laborious and destructive. The goal of this proposal is to realize and validate a multimodal optical imaging platform that uses a single flexible fiber optic interface to acquire non-destructive measurements on-demand from the luminal surface of vascular constructs developing inside a bioreactor. The platform is designed such that three independent but complimentary imaging modalities will be able to operate in parallel, these include fluorescence lifetime imaging (FLIm) for monitoring changes in construct biochemistry; optical coherence tomography (OCT) for monitoring construct morphology and microstructure; and steady state fluorescence imaging (SSFI) to track the proliferation of green fluorescent protein labeled endothelial cells across the luminal surface. The specific aims of this proposal are as follows: (1) To realize a multimodal imaging platform compatible with non-destructive in vitro assessment of the luminal surface regions of vascular constructs inside a bioreactor; (2) To validate the performance of the multimodal imaging platform using tissue phantoms and engineered vascular constructs. The significance of this proposal is it presents an opportunity for a paradigm shift in the assessment of engineered tissue, where conventional destructive techniques are supplanted with faster, non- destructive ones. The innovation of this proposal is that it will allow FLIm, OCT and SSFI to operate in parallel, using the same double-clad fiber interface to guide light to and from the sample. The successful completion of this work has the potential for significant impact in the field of regenerative medicine where supplanting destructive measurements for non-destructive ones will lower costs and allow for faster prototyping of novel biomaterials.